Perchlorate and iodine: a novel focus on newborns
JUPITERIMAGES
levels of perchlorate also characa safe level. Although the contamiFor the first time, scientists have terized the data. Nine out of 13 nant is found in both food and compared a woman’s daily intake infants received levels of perdrinking water, food has emerged of iodine and perchlorate with the chlorate that exceeded the NAS as the primary source of low-level concentrations of each in her recommendation. In the worst exposure for most Americans. Masbreast milk. They found that a case, levels were 3 times higher sachusetts and California have set small proportion (about 20%) of than the NAS safety threshold. drinking-water standards for periodine enters the breast milk The scientists estimate that perchlorate, but the U.S. EPA is still compared with a higher proporchlorate is concentrated in tion (more than 50%) of breast milk 3 times more perchlorate. Although not than iodine is. Thiocyandefinitive, experts say the ate is not concentrated study, published in ES&T with respect to iodine. (DOI 10.1021/es801549w), These concentration efprovides further evidence fects are at least 10 times that iodine intake in U.S. lower than those from mothers is low and that previous in vitro studies, perchlorate could be a and the relative imporproblem for newborns. tance of perchlorate and Perchlorate, a major thiocyanate is also component of rocket fuel, different. also forms naturally. “This work points out Health concerns focus on some very, very important perchlorate’s ability to Does perchlorate from mothers’ breast milk reduce iodine issues,” says thyroid redisrupt thyroid hormone uptake in infants? searcher Thomas Zoeller function by competitively at the University of Massachusetts considering the issue. blocking the uptake of iodine to Amherst. “It is the first time that In the ES&T paper, chemist the thyroid gland and to breast someone has figured out what Purnendu “Sandy” Dasgupta and milk. Iodine is essential to thyroid actually gets into the milk and colleagues at the University of hormones, which orchestrate exposes the infant,” he notes. Texas Arlington recruited nonbrain development in fetuses and “Contaminant effects in in vitro smoking, mainly Caucasian volyoung infants. During breast feedstudies are one thing, but what unteers, aged 24-34, from the ing, the thyroid function of inwe need is to figure out what acmetropolitan Dallas-Fort Worth fants depends on iodine in tually gets into the milk and exarea. The 13 mothers collected maternal milk. poses the infant,” he adds. samples of their own urine in a Previously published in vitro “I remain concerned about the 24 hour (h) period, recorded the data suggested that other conoverall iodine sufficiency of lacvolume, and sent the samples to taminants, notably thiocyanate, tating women in the U.S.,” says Dasgupta’s lab. They also took found in cigarette smoke and vegendocrinologist Elizabeth Pearce four breast milk samples per day etables like cabbage, and nitrate, at Boston University. “It remains for three sets of three consecufound in salad greens, also effecunknown what, if any, effects entive days. “Our study has a small tively block iodine from the thyvironmental perchlorate exposure number of women but lots of roid and breast milk. But this new has on the thyroidal function of data,” says Dasgupta, who added study, sponsored by the Gerber breast-fed infants,” she adds. that 24 h urine samples are a Foundation, suggests that for “We must begin to look at more reliable measure of iodine women who do not smoke, perinfantssbabies 2 weeks to 3 nutrition than spot samples are. chlorate is the contaminant of months oldsin perchlorate studLow levels of iodine characterconcern. ies. What happens to kids in this ized the results. Only one infant In 2005, on the basis of studies age range when all they get is received enough iodine to meet of perchlorate dosing in healthy milk and the perchlorate level is the recommendations of NAS’s adults, a U.S. National Academy of high?” Zoeller asks. Institute of Medicine. Six out of Sciences (NAS) committee recom13 infants received less than mended that 0.7 micrograms per —REBECCA RENNER 30% of this level. Relatively high kilogram of body weight per day is
10.1021/es8024758
2008 American Chemical Society
Published on Web 09/17/2008
November 1, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 7731
